Water, wastewater and industrial liquid filtration units generally include an underdrain system for supporting filter media and for spacing the filter media apart from the filter bottom. In addition to providing support for the filter media, the underdrain system provides other advantages such as collecting the filtered water that passes through the media, and uniformly distributing backwash water, backwash air, or a combination of both, across the filter.
Underdrain systems may include one or more of the following: precast concrete blocks, plastic-jacketed concrete blocks, stainless steel pipe laterals or screens, plastic nozzles or all plastic universal blocks. The underdrain blocks are generally placed side-by-side and end-to-end in the bottom of the filter to provide a “false bottom.” During backwash, the blocks tend to lift off the bottom of the filter and shift out of place, interrupting back wash and allowing sand to enter the effluent pipe and mix with filtered water.
The present invention relates to an underdrain apparatus, and more particularly, to an underdrain apparatus that includes one or more underdrain blocks and an anchoring assembly for securing the one or more underdrain blocks to a filter floor.